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Equivalent Increases in Bone Mineral Density Despite Differences in Training Volume In Growing Rats
Author(s) -
Shdo Suzie M,
Cunningham Ryan M,
Pierce Richard A,
Lee Lucy C,
Ahles Cammie P,
Jaque S Victoria,
Sumida Ken D
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.618.20
Subject(s) - bone mineral , osteocalcin , climb , resistance training , medicine , endocrinology , osteoblast , chemistry , osteoporosis , alkaline phosphatase , biochemistry , engineering , in vitro , enzyme , aerospace engineering
The purpose of this study was to determine if there was an exercise threshold in stimulating an elevation in bone mineral density (BMD), via resistance training, during the growth period in male rats. 27 male rats were randomly divided into Control (Con, n=9), 3 ladder climb resistance trained group (3LC, n=9), and 6 ladder climb resistance trained group (6LC, n=9). The 3LC and 6LC groups were conditioned to climb a vertical ladder with weights appended to their tail 3 days/wk for a total of 6 wks where the 6LC group performed significantly more work compared to the 3LC group. After 6 wks, left tibial BMD (in g/cm2) was significantly greater for 3LC (0.225 ± 0.002) and 6LC (0.234 ± 0.003) compared to Con (0.202 ± 0.004). Further, bone strength (force to failure in Newtons) was significantly greater for 3LC (132.7 ± 4.6) and 6LC (130.0 ± 7.6) compared to Con (102.0 ± 3.4). Serum osteocalcin (OC in ng/ml, a marker for osteoblast activity) was significantly greater for 3LC (50.5 ± 3.4) and 6LC (41.7 ± 2.6) compared to Con (25.0 ± 3.4). There was no significant difference in BMD, bone strength, or OC between 3LC and 6LC. The results indicate that both resistance training programs were equally effective in elevating BMD and bone strength in growing rats. These data suggest that during growth, there is a stimulation threshold where more work per exercise session is ineffective in promoting additional bone formation.